/* Q&A 模态框 */
#qa-modal.qa-modal-overlay {
    position: fixed; top:0; left:0; right:0; bottom:0;
    background: rgba(0,0,0,0.5);
    display: none; align-items: center; justify-content: center;
    z-index: 10001;
  }
  #qa-modal.qa-modal-overlay.active {
    display: flex;
  }
  .qa-modal {
    background: var(--card-bg);
    backdrop-filter: blur(8px);
    border-radius: 10px;
    box-shadow: 0 6px 20px rgba(0,0,0,0.1);
    width: 450px; max-width: 90%; padding: 20px;
    animation: qa-fadeIn 0.2s ease-out;
    font-family: "Segoe UI","Helvetica Neue",Arial,sans-serif;
    color: var(--text-color);
  }
  .qa-modal-header {
    display: flex; justify-content: space-between; align-items: center;
  }
  .qa-modal-close {
    background: transparent; border: none; font-size: 1.3em;
    cursor: pointer; 
    color: var(--text-color);
  }
  .qa-modal-body {
    margin-top: 12px; line-height: 1.5;
  }
  .qa-modal-footer {
    margin-top: 20px; text-align: right;
  }
  .qa-btn {
    padding: 6px 14px; margin-left: 8px;
    border: none; border-radius: 5px; cursor: pointer;
    font-size: 0.9em;
  }
  .qa-prevBtn {
    background: #ccc; 
    color: #333;
  }
  .qa-nextBtn {
    background: var(--accent); 
    color: var(--text-color);
  }
  @keyframes qa-fadeIn {
    from { opacity: 0; transform: translateY(-8px); }
    to   { opacity: 1; transform: translateY(0); }
  }